Silurian rocks are related to which of the following rock systems?

Correct option is A

The correct answer is (a) The Dravidian Rock System

Based on the complex and varied geological history, the Geological Survey of India has classified the rock systems of the country into 4 major divisions:

1. The Archean Rock System
2. The Purana Rock System
3. The Dravidian Rock System
4. The Aryan Rock System

Dravidian Rock System:

• Paleozoic rock formation is known as Dravidian systems in India, formed 600-300 million years ago.
• Dravidian rocks are mostly found in the extra-peninsular regions of the Himalayas and the Gangetic plains.
• Major regions of Dravidian rocks include Pir Panjal, Handwara, Lider Valley, Anantnag of Kashmir, Spiti, Kangra, and Shimla region of Himachal Pradesh, Garhwal and Kumaon of Uttarakhand.
• Dravidian rocks include shales, sandstones, clays, quartzites, slates, salts, talc, dolomite, marble, etc.
• Dravidian period saw plenty of fossil evidence, indicating marine conditions in these Paleozoic rocks in India.
• The Cambrian, Ordovician, Silurian, Devonian, and Carboniferous systems are included in the Dravidian system of geological formations.
• Dravidian period marks the beginning of coal formation (high-quality Carboniferous coal), but these formations were not found abundantly in India.
• It is the period when Pangaea was broken and Tethys Sea came into existence.

Carboniferous rocks (350 million years):

• These rocks are composed mainly of shale, quartzite, and limestone.
• Mount Everest is made up of Upper Carboniferous limestones.
• Coal formation began in the Carboniferous age.
• The term Carboniferous means coal-bearing.
• Most of the coal found in India is not from the Carboniferous period.
• High-quality coal of the Great Lakes region-USA, UK, and Ruhr region is carboniferous coal.

Additional Information:

Archaean Rock System (Pre-Cambrian):

• Age: >2,500 million years.
• Features: Oldest rocks, devoid of fossils, mostly igneous and metamorphic rocks.
• Examples: Dharwar system, granite, and gneisses.
• Distribution: Peninsular India (Karnataka, Tamil Nadu, Odisha).

Purana Rock System (Proterozoic):

• Age: 1,500–600 million years.
• Features: Sedimentary rocks, rich in limestones and sandstones.
• Examples: Cuddapah and Vindhyan systems.
• Distribution: Cuddapah basin (Andhra Pradesh), Vindhyan ranges (Madhya Pradesh, Rajasthan).

Aryan Rock System:

• Age: 570 million years to the present.
• Features: Sedimentary rocks, fossil-rich deposits, coal, petroleum formations, and basaltic lava flows (Deccan Trap).
• Examples: Gondwana System (coal), Jurassic System (marine fossils), Deccan Trap (lava), Tertiary and Quaternary Systems (alluvial/glacial deposits).
• Distribution: Gondwana (Damodar Valley, Son Valley), Jurassic (Kutch, Jaisalmer), Deccan Trap (Maharashtra, Gujarat), Tertiary and Quaternary (Indo-Gangetic plains, Assam).